OVERALL OBJECTIVES: The overall aim of the proposed research program is to study various metabolic activation and inactivation processes involved in carcinogenesis by various chemicals. It is proposed to investigate whether metabolic N-hydroxylation and ring-hydroxylation of 2-acetylaminofluorene, dealkylation of dialkylnitrosamines, epoxidation of benzo(a)pyrene and aflatoxin B1 are occurring through single or multiple cytochromes P-450 present in the endoplasmic reticulum of liver and other tissues of various animals. Modifications of cytochromes P-450 via phosphorylation, methylation and acetylation will also be investigated in vivo and in vitro studies. Role of cytochrome b5 and phospholipids will be examined in oxidation of various carcinogens. Cholate solubilized cytochromes P-450 and b5 will be purified by affinity and ion exchange column chromatography. Immunological technics will also be used for study of these proteins. High pressure liquid chromatography in conjunction with radioactivity will be used for separation and quantitation of several carcinogen oxidation products. In some cases, covalent binding of a carcinogen moiety to DNA will be used as an index of carcinogen activation.